1. Field of the Invention
This invention relates to a water-based liquid detergent which contains hydrogen peroxide as bleaching agent and which is distinguished by high stability in storage and easy dosing and by a process for its production.
2. Discussion of Related Art
Both non-aqueous and aqueous liquid detergents containing bleaching per compounds are known. In non-aqueous detergents, the per compounds typically added in the form of solid perhydrates or per salts are generally not difficult to stabilize. However, difficulties are often involved in stabilizing the detergents against separation. These difficulties are normally counteracted by adjusting the detergents to a high viscosity and grinding the ingredients to a very small particle size by an elaborate grinding process carried out in colloid mills. In many cases, sedimentation stabilizers also have to be added. Another disadvantage is that relatively large quantities of inflammable organic solvents often have to be added. Detergents of the type mentioned are described, for example, in DE 12 79 878 (GB 1,205,711), DE 22 33 771 (U.S. Pat. No. 3,850,831), DE 28 25 218 (U.S. Pat. No. 4,316,812) and Ep 30 086.
In water-based liquid detergents, in which the ingredients are dissolved and hence are generally more resistant to phase separation, considerable difficulties are involved in stabilizing oxygen-containing bleaching agents. According to DE 10 80 722, highly condensed phosphates are added to the detergents which are then adjusted to a pH value of 6 to 6.5. On account of their phosphate content, the detergents have a eutrophicating effect in wastewater. In addition, the detergents are paste-like on account of their high percentage content of nonionic surfactants and, accordingly, cannot be measured out with measuring cups, as preferred by consumers. The detergents described in DE 15 67 583 (U.S. Pat. No. 3,658,712) contain a special crosslinked polymer as stabilizer which also thickens the detergents to a considerable extent so that they are difficult to dose. Finally, according to EP 38 101, the particles of bleaching agent are encapsulated and are suspended in the detergent in this form. Unfortunately, there are no details in this document as to the nature of the encapsulating material which, logically, must be stable or rather insoluble in the water-based detergent concentrate, but unstable or rather readily soluble in the aqueous wash liquor.
The problems discussed in the foregoing are solved by the present invention.